Rhoda Williams (Brit Marling), a brilliant 17 year old girl who has spent her young life fascinated by astronomy, is delighted to learn that she has been accepted into MIT. In a reckless celebratory moment, she drinks with friends and drives home intoxicated. Listening to a story on the radio about a recently discovered Earth-like planet, she gazes out her car window at the stars and inadvertently hits a stopped car at an intersection, putting John Burroughs (William Mapother) in a coma and killing his wife and son. Rhoda is a minor, so her identity is not revealed to John. After serving her prison sentence, and after 4 years of isolation, Rhoda continues to shield herself from the world outside, becoming a janitor at a local school, wanting to work "physically", almost as a means to struggle past the potential she has squandered with the decision of a single night. More of the movie here.